gearbox

[kennatt]

just lost top gear after giving the splitty a blast out, will not select top properly sometimes goes in and stays others(Mostly) throws the gear out.You can feel that it's not engaging,think best solution would be a secondhand box rather than a strip down probably selector forks worn or syncro. so in market for a 948 box if anyone has a known decent one.Then I may rebuild mine at my leisure,strange that There was no previous warnings,just suddenly threw the gear after a quick change up.Distance no object can arrange my own carrier but would prefer north east england if possible. Cheers

[bmcecosse]

Yet it works normally in all other gears ? I would check the lever mechanism for any looseness/free play. 4th gear is a direct drive, so usually pretty much troublefree. But it could be bearing [problems. As you suggest - another box will be the best way forward in the short term.

[kennatt]

yes all others are ok when it actually goes into top even from 60mph if you take your foot off it stays in gear with no sign of jumping out. but most times it will go sort of just in then when I let clutch out slips straight out,can be held in with a bit of force as you say unusual for this sort of fault in top, mainly lower gears, can't quite work out why. Might take the cover off and have a look .Just dosen't feel as though it is actually meshing into the gear

[bmcecosse]

Check all the lever/extension mech in case something has come loose and is blocking the movement - maybe even just the top 3 bolts allowing the lever to come loose?

[kennatt]

already tried the three bolts,I think it may be the selector fork rod bolt since It happened the first time then second try engaged and ran fine for the next 10 mile changing ok then it started again and eventually will not engage properly.going to drop the box and have a look

[bmcecosse]

Well you can get at the fork through the side plate - so just drain and remove the plate as a first check.

[kennatt]

did that last night and can't see anything loose so looks like a box swap,shame because it was a very quiet and dry box no crunching even on rapid gears changes

[MarkyB]

If you can get the floor out it would be worth removing the remote from the top of the box, the lever that goes into the box can get loose on the shaft.

[kennatt]

did that and put into top straight from gear box still jumps out,checked all springs and plungers all ok grove in selector rod dosn't look worn,everybody I have spoken to including a guy That has had lots of dealings with these boxes(Miget rebuilder) and a guy at easygears rebuilders they all say ..........neverheard of this sort of problem yes well worn ones will throw top gear out on the overrun,but once drive is taken the gears tend to drive into each other an hold. Looks like another box and then I'm going to strip the old one to see if I can see what has caused it,Could do with the practice about 20 years since I had a box in bits (Sad eh,nothing else to do need another rebuild project maybe)

[bmcecosse]

I agree - most unusual problem.

[kennatt]

well found it I think decided to take box out and fit another that I have managed to find.Once out it was clear that the first motion shaft bearing had broken up, the first motion shaft was flopping about and you could see the bearing in the casing moving in its housing, This wasn't seen with the box in situ because the clutch and spiggot bush in the engine were holding the end of the first motion shaft and preventing any movement by hand but obviously on drive it was thrashing about and so must have been causing a missalignment of fourth gear,it wouldn't effect third because the gear is at the rear of the box so less movement on the shaft.Strange that there was absolutly no noise from the box,and mental note to check the state of the spiggot bush (Could be that, worn or missing, and that has caused the bearing to fail in the first place) This has to be the fault cos I can't see anything else wrong inside .Dont know if its worth trying to rebuild it, From memory I think you need a full stripdown to replace that bearing because it is driven in from inside the box .have to get the books out.Now that I'm at this stage going to take engine out to clean up the engine bay and put a new friction plate into the clutch and much easier to mate the engine and box out of the car to refit.

[bmcecosse]

I was going to suggest bearing failure - but you hadn't mentioned any strange noises. I think it will be well worth rebuilding if it was otherwise working ok. Put a new syncro ring in 2nd gear - and check the layshaft/bearings while in there!

[MarkyB]

Is there a spigot bearing in the middle of the flywheel?
The lack of one would put extra strain on the bearing.

[kennatt]

yes may rebuild but am told by chris at tom roys that everyone now want to fit the later 1098 box and theres not much demand for the old 948 although still obviously worth £100 so may be worth it to me,and yes as mentioned will be having a CLOSE look at the spigot bush,although I know there is one fitted from the last engine out 15 years ago,but could have broken up,and yes BM absolutly no noise from the box thats where it threw me right from the start,I think it simple packed up there and then and started to kick the gear out at the same time I suppose after 56 yearsof spinning it simply kicked the bucket, so to speak,when its my turn hope I go as quick hate to grind away and become a grumbly old fart

[linearaudio]

Its your money!! If the box is already out and all other gears were fine, I would be tempted to put a new front bearing in, and as a matter of course, replace the needle bearing between 1st and 3rd shaft. The box is easy to strip, but needs a certain simple approach regarding drifting 1st and 3rd shafts with their bearings out with a suitable screwdriver/ hammer mx . There does exist a very helpful WSM download somewhere... BMCEcosse may just be able to locate the relevant link .
Don't be put off by any implied technology of the moggy box- I have 3 which I am juggling with at the moment- hardest bit seems to be registering the tail section with the main box on re-assembly, but hardly mind boggling stuff!!

[bmcecosse]

£100 for a 948 box?? A bit over the top!! Yes the 1098 box is obviously better - but the 948 box is fine for a 948 engined car. Some of the bits are hard to get now - but bearings are easy.

[kennatt]

oh I'm quite confident in being able to strip and rebuild it but at the moment I'm in the process of a full rebuild of my Scimitar GTC just finished the repaint after a back to gel coat strip and now have to refurbish the interior,so really couldn't be botherd to rebuild the box(Not yet).Needed to get the minor back into use as a daily driver,because I was convinced my old transit would fail the mot unless I spent time on it,hence the sudden grab of a box from tom roys, yes overpriced I agree,but the van passed with a couple of advisories.So the scimitar is now outside and the minor is over the pit to sort out. Sometimes wonder if it would be better to sell the lot and buy a mondeo No just joking

[bmcecosse]

Let's see some Scimitar pics!!

[lambrettalad]

Hi
not having driven a moggie with an old style gear box ,I found it useful to remember it has three moving gears 2nd 3rd and 4th and two stationary gears 1st and reverse,also the gates are more like a X rather than a H

I remember cupping my hand whist changing gear ,still do it today,having re-educated my left foot, brain and hand

[kennatt]

Yes will put some photos on as soon as I get my camera back from my daughter who borrowed it for a couple of hours three weeks ago